1. Field of the Invention
The present invention relates to an oil-based cleansing composition, and in particular, relates to the prevention of transparency decrease due to interfused water.
2. Prior Art
Cleansing compositions can be broadly classified to water-based cleansing compositions and oil-based cleansing compositions. As water-based cleansing compositions, there are lotion type compositions which consist of an ethanol aqueous solution of a surfactant and aqueous gel-type compositions, in which the surfactant is thickened with a polymer. As for the oil-based cleansing compositions, there are cream type compositions, which can achieve a cleansing function, during massage, by the inversion of an O/W emulsion, and oil type compositions (cleansing oil) that consists of an oil solution of a surfactant.
Among these, the oil type composition is known to have a high cleansing effect. In recent years, the favorable makeup is of the type, with which the secondary adhesion of foundation or lipstick is prevented, and of the type, in which high-polymer silicone is contained, such as mascara. Thus, the demand of the oil type composition in the market is becoming very high.
The oil type composition consists of a nonionic surfactant, an oil component, and a small amount of water, and they forms a reverse micellar solution, in which the surfactant forms aggregates in the oil component by arranging hydrophilic groups along the inner side. Water is solubilized in the core of the micelle where the hydrophilic groups gather, and the prepared 1-phase solution is completely transparent.
In the ability to take water completely in a transparent state, namely, in the solubilizing power, the oil type composition has a limitation, because of its microstructure. When water is interfused beyond the solubilizing power, the coexistence with another phase (two phase state) takes place, that is, a water-in-oil type or an oil-in-water type emulsion is typically formed. When the size of the internal phase particles becomes more than a certain size, the solution turns into white turbidity, as a whole, because of scattered light due to the difference in the refractive indexes of the two phases. In this case, the preferable cleansing performance and smoothness of massaging may not be achieved depending upon the coexisting phase. In addition, white turbidity is undesirable because it strongly suggests decreased the performance to consumers.
Thus, an oil-based cleansing compositions cannot be used in a bath with wet hands; in addition, it cannot be used on a wet face after shampooing hair, thus restricting the usage.
It is described that a cleanser that easily adapts to makeup even if the skin is wet (Japanese Patent Publication 2000-327529). This was achieved by simultaneously using a polyglyceryl fatty acid ester that has the HLB of not less than 10 and a polyhydric alcohol that is trihydric or more. However, the white turbidity could not be prevented by this method, and the smoothness of massaging was often not sufficient.
It is described that cleansing compositions with high cleansing performance, even when used with wet hands (Japanese Patent Publication Hei 6-16524, and Japanese Patent Publication 2001-270809). They were prepared by combining a nonionic surfactant and an amphoteric surfactant or by combining a nonionic surfactant and a glyceryl ether derivative. However, the smoothness of massaging and the prevention of white turbidity were not consistently satisfactory.
An objective of the present invention is to provide a safe oil-based cleansing composition that has little eye irritation and has high cleansing performance, no white turbidity, and no reduced smoothness of massaging even when water is interfused.